However as today's poll shows that Leave is not only catching
Remain, but may actually have a lead, the markets are reacting
negatively.

Accendo Markets' Mike van Dulken told Business Insider:

The driver this afternoon is the latest poll showing the Leave
camp taking a surprise lead, undoing of a lot of the currency’s
recent good work to get back above 1.46 and sit close to 2016
highs.

Polls of late had been showing the Remain camp comfortably in the
lead, in some cases by quite a margin, which had helped GBP and
many UK-exposed stocks rally on the prospect of the status quo
being better than a jump into the unknown. The latest ICM phone
poll shows a reversal of an 8pt lead by Remain to a 3pt deficit
in the space of just 2 weeks. With less than three weeks to go
though, be prepared for the polls to swing around even more as
both camp trade blows over the merits of their respective
campaigns.

Currency traders in the City of London are broadly expecting a
Brexit to have a huge negative impact on the pound, with
Joe Rundle of ETX Capital telling Business Insider last week
that: "We're planning for a 20% fall in Sterling and a 20%
rise in dollar, so a 40% move. We're planning for an instant move
— no trading and no liquidity in between the two moves. We're
always stress-testing our systems but this is such a big event
that you have to plan on extremes."